The role of sequestering agents in softening water by complexing the "hardness" cations in water supplies is well known. Sequestering agents are recognized aids in detergent processes because they form a soluble complex with calcium and magnesium ions which can react with soaps and other anionic surfactants and otherwise adversely affect detergency. Polyphosphates such as tripolyphosphates and pyrophosphates are widely used as ingredients in detergent compositions in part because of their property of sequestering hardness ions. Such phosphorus-containing compounds as well as nitrogen containing compounds, e.g., nitrilotriacetates, are highly effective. However, the effect of the phosphorus content and the nitrogen content of these sequestering agents upon eutrophication of lakes and streams has been questioned and the use of phosphates in detergent compositions has been subject to government regulation or prohibition.
These circumstances have developed a need for highly effective and efficient phosphorus-free and nitrogen-free sequestering agents and detergency builders.
The object of the present invention is to provide such a class of compounds which are useful as sequestering agents, especially when used as builders in detergent compositions containing surfactants.
U.S. Pat. No. 3,293,176, issued Dec. 20, 1966, to White, discloses ether chelating compounds having carboxylic acid, phosphoric acid or sulfonic acids groups.
U.S. Pat. No. 3,692,685, issued Sept. 19, 1972 to Lamberti et al., discloses detergent compositions containing an ether polycarboxylate having the formula: ##STR1##
U.S. Pat. No. 4,228,300, issued Oct. 14, 1980, to Lannert, discloses ether polycarboxylate sequestering agents and detergency builders having the formula ##STR2## wherein M is alkali metal or ammonium, R.sub.1 and R.sub.2 are hydrogen, methyl or ethyl and R.sub.3 is hydrogen, methyl, ethyl or COOM.
U.S. Pat. Nos. 3,923,679, issued Dec. 2, 1975, and 3,835,163, issued Sept. 10, 1974, both to Rapko, disclose 5-membered ring ether carboxylates. U.S. Pat. Nos. 4,158,635 issued June 19, 1979; 4,120,874, issued Oct. 17, 1978, and 4,102,903, issued July 25, 1978, all to Crutchfield et al. diclose 6-membered ring ether carboxylates.
It is a purpose of the present invention to provide new and superior ether polycarboxylate sequestering agents, detergent compositions containing said sequestering agents and a method for making said sequestering agents.